Concept explainers
Which of these is not a characteristic of synaptic potentials?
Want to see the full answer?
Check out a sample textbook solutionChapter 7 Solutions
Human Physiology
- Which of the following is true about the conduction of action potentials? a. Thicker axons are faster because there is more surface area on thicker axons. b. Myelin speeds conduction because the glial cells add voltage gated Na+ channels to the neuron. c. Diffusion of Na+ ions between the Nodes of Ranvier happens faster than the wave of opening and closing membrane proteins can travel. d. Neurons that don’t have myelin sheaths undergo saltatory conduction e. Action potentials move slowly.arrow_forwardAction potentials are normally initiated at the axon hillock because a. there is a particularly high density of voltage-gated sodium channels there. b. threshold potential is lower there than at other sites along the plasma membrane. c. activation of sodium channels at the axon hillock results in a particularly strong inward current and consequent depolarization. d. all of these. e. none of these.arrow_forwardWhich of the following is TRUE regarding the absolute and relative refractory periods of the action potential (AP)? A. The absolute refractory period may be overcome if enough excitatory stimulation is applied to the neuronal membrane. B. The absolute refractory period is due the closing of the activation gate of voltage gated sodium channels at the peak of the AP. C. The relative refractory period is due to the closing of the activation gate of voltage gated potassium channels during the overshoot phase of the AP. D. The relative refractory period is due the closing of the inactivation gate of voltage gated sodium channels . E. All of the above statements are FALSE.arrow_forward
- Sequence the following list of events of a neuronal action potential by placing 1 next to the first event, 2 next to the second event, and so on. a. _____ The activation gates of voltage-gated Na+ channels open, Na+ flood the cytoplasm, and depolarization occurs. b. _____ K+ continue to flow out of the axon until the membrane is hyperpolarized. c. _____ Local potentials cause the membrane to depolarize to threshold. d. _____ The inactivation gates of voltage-gated Na+ channels close as voltage-gated K+ channels open, K+ begin to exit the axon, and repolarization begins. e. _____ Repolarization continues and Na+ channels return to restingarrow_forwardWhat statement about synapse activity is false? A.The input of sodium ions by AMPA receptors is triggered by glutamate binding to the same receptors.B.Calcium entering the dendritic spine during synaptic transmission activates proteins that can potentiate synapse.C.Depolarization of the membrane caused by the arrival of calcium ions makes it possible to eject sodium blocking NMDA receptors.D.Glutamate can be released by the pre-synaptic button following the arrival of an action potential via the axon.arrow_forwardDuring the depolarization phase of an action potential, the permeability of the membranea. to K+ is greatly increased.b. to Na+ is greatly increased.c. to Ca2+is greatly increased.d. is unchanged.arrow_forward
- During an action potential, the inside of the cell membrane becomes more positive than the outside. Why does this happen? a. During depolarization, the sodium ions rush in and the potassium ions have not begun rushing out, making the inside more positive. b. During depolarization, the sodium ions rush in and the potassium ions have not begun rushing out, making the outside more positive. c. During depolarization, the potassium ions rush in and the sodium ions have begun rushing out, making the inside more positive. d. During depolarization, the sodium ions rush in and the potassium ions have begun rushing out, making the outside more positive.arrow_forwardThe nerve impulses always travel in one direction from dendrites to axon terminals. What prevents an action potential from travelling backward? a. Hyperpolarization of the neuron makes the membrane more positive and prevents another action potential. b. After repolarization, the refractory period occurs, where the sodium ions are found outside the cell. c. After repolarization, the reversal of ions prevents another action potential as there would not be enough sodium ions outside the cell to rush in. d. The refractory period prevents another action potential by lowering the threshold potential.arrow_forwardWhich of the following statements is TRUE of the action potential? A. At the peak of the action potential there are approximately an equal amount of open voltage gated sodium and potassium channels B. To reach threshold the action potential requires the activity of sodium potassium pump C. During the rising phase (prior to the peak) of the action potential more voltage gated sodium channels are open than voltage gated potassium channels D. None of the choice options are TRUE of the action potential E. The overshoot phase (below resting membrane potential) is a result of voltage gated sodium channels taking a long time to close.arrow_forward
- The axon hillock of a neuron reaches the threshold of excitation and the membrane potential becomes completely reversed. Then, suddenly, the membrane potential begins to return to resting membrane potential. What is the event that triggers this return to resting potential? A. Na+ channels close in a voltage-dependent manner B. Na+ channels close in a time-dependent manner C. Na+ channels close in a chemically-dependent manner D. Na+ channels open in a voltage-dependent mannerarrow_forwardPost synaptic neurons membrane potentials are less negative than resting membrane potentials when this occur A. Creates a new set point for the resting membrane potential B. Has a lower propensity to produce an action potential C. Reacts by generating action potential D. Higher chance of reaching the potential thresholdarrow_forwardThe two primary factors that influence the speed of an action potential propagation are axon diameter and a. myelination. b. the type of associated glial cell(s). c. concentration of K+ in the cell. d. the length of the axon.arrow_forward
- Human Anatomy & Physiology (11th Edition)BiologyISBN:9780134580999Author:Elaine N. Marieb, Katja N. HoehnPublisher:PEARSONBiology 2eBiologyISBN:9781947172517Author:Matthew Douglas, Jung Choi, Mary Ann ClarkPublisher:OpenStaxAnatomy & PhysiologyBiologyISBN:9781259398629Author:McKinley, Michael P., O'loughlin, Valerie Dean, Bidle, Theresa StouterPublisher:Mcgraw Hill Education,
- Molecular Biology of the Cell (Sixth Edition)BiologyISBN:9780815344322Author:Bruce Alberts, Alexander D. Johnson, Julian Lewis, David Morgan, Martin Raff, Keith Roberts, Peter WalterPublisher:W. W. Norton & CompanyLaboratory Manual For Human Anatomy & PhysiologyBiologyISBN:9781260159363Author:Martin, Terry R., Prentice-craver, CynthiaPublisher:McGraw-Hill Publishing Co.Inquiry Into Life (16th Edition)BiologyISBN:9781260231700Author:Sylvia S. Mader, Michael WindelspechtPublisher:McGraw Hill Education